Causes of ischemic diseases of organs are conventionally known to be roughly classified into hematogenous disorder and functional disorder of organs themselves. For hematogenous disorder, an evaluation index and a diagnostic technology to suggest a therapeutic strategy in a noninvasive manner has been sought after. Stenosis, which is an example of coronary hematogenous disorder, is a serious lesion leading to ischemic heart disease. For such ischemic heart disease, it is necessary to determine whether pharmacological treatment, stent treatment, or the like should be provided.
In recent years, measurement of fractional flow reserve (FFR) under guidewire control in coronary angiography (CAG) using catheters is being recommended for diagnosis with coronary hematogenous ischemic evaluation. However, for example, if coronary hematogenous ischemia can be evaluated with use of medical images of the heart collected by a medical image diagnostic apparatus, such as an X-ray computed tomography (CT) apparatus, a magnetic resonance imaging (MRI) apparatus, and an ultrasound diagnostic apparatus, the need of catheter surgery may be eliminated.